For reference: a few years ago I lived in an apartment where I counted at least 35 different 2.4 GHz networks. This wasn't even a high-rise but in a street with

For reference: a few years ago I lived in an apartment where I counted at least 35 different 2.4 GHz networks. This wasn't even a high-rise but in a street with normal 3 story apartment buildings. Wifi only worked on channel 13 reliably because many access points don't include channel 13 in their "random channel" configuration because it's only available in Europe.